Electricity is the primary energy source used in our everyday lives. It is used to light our homes, keep us cool/warm, and it powers endless technology that is used on a day to day basis. The Energy Grid in the United States is primarily powered by coal, natural gas, and nuclear reaction. In 2014, 39% of the electricity generated was through using coal, natural gas was used for roughly 27%, nuclear reaction 19%, and hydropower and other renewable sources was used for the remaining percentage. But just how ‘clean’ are these methods of producing electricity?
Coal is the most used fuel to create energy around the world. This organic sedimentary rock is made of decomposed plants from millions of years ago and can be found in underground deposits gloabally. These deposits are easily accessible making coal cheaper than other methods of electric gen
eration. Converting coal into electricity is a multistep process and is performed by coal plants. The first step is crushing the coal into a fine powder. They then use the powder as fuel in a furnace. The furnace heats a boiler, which holds water, to create steam. The steam turns a turbine engine which powers a generator, creating electricity. Although this resource is easily accessible and is used globally, coal plants are among the top sources of carbon dioxide emissions. Burning coal produces nitrogen oxides, sulfur dioxide, and carbon dioxide. A typical coal plant in the United States generates 3.5 million tons of carbon dioxide per year. Coal may be the cheapest resource of generating electricity, but it is the dirtiest.
Throughout the years, there has been an increased use of natural gas to generate electricity. Steam generation units can a
lso be used with natural gas, just like with coal. Although, basic steam generation units are usually not that efficient. According to reports, only about 33-35% of the thermal energy used to generate the steam is converted into electricity. Electric generation can also be achieved through the use of a gas turbine fueled by natural gas. This system uses hot gases released by the burning of natural gases to turn a turbine to generate electricity. Combined-cycle plants recycle the waste heat from the gas turbine and used to generate steam to increase natural resource efficiency. These plants can achieve thermal efficiency of 50-60% making them much more efficient that coal plants. Like coal, natural gas emits both nitrogen oxides and carbon dioxide but at lower rates, nearly half the C02 emissions of coal.
There are nearly 100 nuclear facilities in 30 different states in the U.S. that are responsible for almost 20% of the energy grids electric generation. Nuclear reactors are powered by uranium. Reactors produce and control energy that is acquired through the splitting of uranium atoms. This harnessed energy is then used in the same manner as coal plants and combined-cycle plants; water is boiled to make steam which drives turbine generators. This process is a much cleaner and efficient way of producing electricity. Greenhouse gases are not a byproduct of nuclear reaction. According to reports in 2014 nuclear energy facilities prevented 595 m
illion metric tons of C02 emissions, 1 million short tons of sulfur dioxide, and 0.48 million short tons of nitrogen oxide which would have been polluted the atmosphere if electric generation was done by coal plants and combined-cycle plants. Although nuclear reaction might seem like the most efficient way of producing electricity, there are numerous risks associated with the process. For example, if a serious accident were to occur at a nuclear power plant dangerous amounts of radiation would enter the environment and would result in disastrous damages. There is also an increased risk of cancer for those individuals exposed to the radiation. Radioactive waste is the byproduct of nuclear reaction. This waste is often kept at the nuclear facilities for a certain period of time while the level of radiation decays until it is safe to be buried deep in the ground.
In order for the nation to become more efficient and produce less C02 emissions, the use of coal plants must be replaced by cleaner and more efficient methods of generating electricity. Even transforming the current coal plants into combined-cycle plants would prove very effective in the short run considering natural gas produces half the emission of coal.
Source 1: http://www.eia.gov/tools/faqs/faq.cfm?id=427&t=3
Source 2: http://www.peabodyenergy.com/content/178/coal-fueled-electricity
Source 3: http://www3.epa.gov/climatechange/ghgemissions/sources/electricity.html
Source 4: http://naturalgas.org/overview/uses-electrical/